A screw, through the physical and mathematical principle of the frictional force of the inherent via increasing helical threads around the sloping outside and sloping track on its (bolt and nut) surface, can tightly fasten two or more objects with screw threads. It has been widely used for coupling and fastening since ancient time in all kinds of machineries, equipments, transportation facilities such as vehicles and engines, railway bridges, main and ancillary building structures, various types of tools and instruments, and household electric appliances and consumer electronic products, etc. A screw fastening assembly can achieve high strength connection, resist torsional rupture, resist impact loosening or fracture, resist fastening abrasion and provide repetitive use function.
A conventional screw aims to connect two or more machinery structure elements to enlarge the equipment size to make a bigger product or extend continuous production capability of the product. The conventional connecting screws mostly are used to closely fasten two mechanical structure elements without escaping a pre-design control space. The two objects fastened by a conventional screw are merely to bridge or transmit their physical characteristics, such as support gravity continuity, continuous transmission of action force and counteraction force, thermal transmission, or the like. But on expensive and important equipment, during transmission of physical characteristics at many important or critical contact points, quality and quantity changes do not generate physical data detection and signal output function. However, U.S. Pat. No. 2,873,341 entitled “Electric strain gauge and resistance” assigned to Ali Umit Kutsay et al, referring to FIG. 1, discloses a resistance sensing bolt strain gauge with an embedded screw resistance wire to sense a small change of the length of the bolt when the screw is compressed, and the small change of the length of resistance wire causes change of resistant value. Such a technique had been adopted ever since. As shown in FIG. 1, it includes a bolt 10, a central bore 11, an interval 12 one inch deep from the upper edge, two suitable cross holes 13 and 14 in the bolt, a head of the bolt 15, a core 16 made of Epoxy potting compound, a resistance wire 17, two leads 20 and 21 from two ends of the resistance wire 17, two distal ends 22 and 23 where the two leads 20 and 21 connect to the resistance wire 17, and a lead interval 24 between the leads 20 and 21. Because it uses an electronic resistance element structure to form a circuit, the signal caused by small current change due to resistance variation is easily affected by electromagnetic waves or magnetic noises generated in the test environment and distorted. As a result, the requirement of getting online signal or instant response in the present digital age is still not being met to date. For hundreds of years the screws have played an important and critical role and function in the progress of society, they have to be viewed in a new perspective and given an updated function and mission along the progress of time. This is a goal yet to be met in the screw industry.
In addition to the existing function provided by the screw in the prior art, to make further exploitation of its inherent physical data to complement its fastening function, and display and output those data and control specific functions are a commendable goal this invention aims to pursue.